Sound source circuit and telephone terminal using same

ABSTRACT

A sound source circuit is provided for a telephone terminal to reproduce chorus-effect imparted musical tones as incoming call sound or hold sound. Herein, original musical tone data ω c 1  are slightly modified in pitches to produce musical tone data ω c 2  with respect to a prescribed tone color. These musical tone data are periodically selected and synthesized together to form musical tone signals having a chorus effect, based on which the chorus-effect imparted musical tones be reproduced for the telephone terminal such as a portable telephone.

This application is the National Phase of International ApplicationPCT/JP00/08422 filed Nov. 29, 2000 which designated the U.S.

TECHNICAL FIELD

This invention relates to sound source circuits and telephone terminalsusing sound source circuits, which are preferable for use in portabletelephones, automobile phones and small game devices.

BACKGROUND ART

Conventionally, when portable telephones and automobile phones receivecalls, beep sounds are produced to notify users (or subscribers) ofreception of incoming calls. However, beep sounds are offensive to earsof the users, so recently sound source circuits are frequently providedinside of the portable telephones to produce melody sounds as incomingcall sounds.

It is required that the sound source circuits used in small-size devicessuch as portable telephones be reduced in size and inexpensive in cost.For this reason, monophonic sound source circuits are normally used inthe portable telephones. However, the monophonic sound source circuitsonly produce sounds that are monotonous and thin in sound quality. Tocope with such disadvantages, it is possible to propose an idea in whichchorus effects are imparted to sounds to provide rich sound quality.Conventionally, imparting chorus effects to sounds is implemented byusing effectors (or effect devices) following the sound source circuits.However, the sound source circuits coupled with the effectors arecomplicated in configuration and expensive in cost. Therefore, it isimpractical for engineers to employ the sound source circuits coupledwith the effectors for use in the portable telephones.

It is an object of this invention to provide a sound source circuit anda telephone terminal using it by which chorus effects can be imparted tosounds for notifying users of reception of incoming calls with a simpleand inexpensive configuration.

DISCLOSURE OF INVENTION

A telephone terminal comprises a sound source circuit to reproducechorus-effect imparted musical tones as incoming call sound or holdsound. Herein, there are provided at least two kinds of musical tonedata, namely, original musical tone data ωc1 and pitch-modified musicaltone data ωc2 that are slightly modified in pitches compared with theoriginal musical tone data. These musical tone data are periodicallyselected by each prescribed period and are synthesized together to formmusical tone signals having a chorus effect, based on whichchorus-effect imparted musical tones are produced for the telephoneterminal such as a portable telephone.

Upon receipt of an incoming call from a calling party, the telephoneterminal rings the incoming call sound corresponding to thechorus-effect imparted musical tones to make notification to a calledsubscriber. When the called subscriber holds the telephone terminal fora while, the telephone terminal transmits signals representing the holdsound corresponding to the chorus-effect imparted musical tones to thecalling party.

Using the chorus-effect imparted musical tones, it is possible togenerate the incoming call sound or hold sound for the telephoneterminal with diversity and variety of sound. In addition, thisinvention provides a simple configuration to realize the chorus effectwithout using an effector which is complicated and expensive.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a configuration of a sound sourcecircuit in accordance with a first embodiment of the invention.

FIG. 2A shows an example of a waveshape of input musical tone datahaving a frequency f.

FIG. 2B shows an example of a waveshape of output musical tone datahaving a frequency f+α.

FIG. 3 shows an example in replacement of essential parts of the soundsource circuit of FIG. 1.

FIG. 4 shows another example in replacement of essential parts of thesound source circuit of FIG. 1.

FIG. 5 shows a further example in replacement of essential parts of thesound source circuit of FIG. 1.

FIG. 6 is a block diagram showing a configuration of a telephoneterminal in accordance with a second embodiment of the invention.

FIG. 7 is a block diagram showing an internal configuration of a musicaltone playback circuit shown in FIG. 6.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention will be described in detail by way of examples withreference to the accompanying drawings.

FIG. 1 shows a configuration of a sound source circuit 1 in accordancewith a first embodiment of this invention. That is, the sound sourcecircuit 1 of FIG. 1 is designed to form musical tone signals based onthe FM modulation method. Herein, reference symbol T1 designates aterminal that receives tone color data ωm for determination of a tonecolor of musical tones; reference symbol T2 designates a terminal thatreceives musical tone data ωc1 for designating pitches of musical tones;and reference symbol T3 designates a terminal that receives a periodicsignal Sa. In addition, a musical tone data conversion circuit 2converts the musical tone data ωc1 to musical tone data ωc2, whichslightly differ from ωc1 in value. For example, the musical tone dataωc2 is produced by adding small numeric values such as ‘1’ and ‘2’ tothe musical tone data ωc1 or by subtracting the small numeric valuesfrom the musical tone data ωc1.

A phase generator 3 generates modulation signals (or digital signals)and is constituted by a sawtooth wave generation circuit for generatingsawtooth waves having slopes corresponding to the tone color data ωm,and a sine wave table. That is, the sine wave table is accessed byoutput data of the sawtooth wave generation circuit, so it is possibleto output sine waves having frequencies corresponding to the tone colordata ωm as follows:B sin ωmt

The periodic signal Sa is periodically changed in value between ‘1’ and‘0’, and it is supplied to a selector 4 that selectively outputs themusical tone data ωc1 or ωc2. That is, the selector 4 outputs themusical tone data ωc1 when the periodical signal Sa is ‘1’; or theselector 4 outputs the musical tone data ωc2 when the periodic signal Sais ‘0’. An operator 6 outputs sine waves that have a frequencycorresponding to an output (i.e., ωc1 or ωc2) of the selector 4 and thatare produced by effecting frequency modulation using sine waves outputfrom the phase generator 3. That is, the operator 6 is constituted by asawtooth wave generation circuit for generating sawtooth waves havingslopes corresponding to the musical tone data ωc1 or ωc2, an additioncircuit for adding together an output of the sawtooth wave generationcircuit and an output of the phase generator 3, and a sine wave table.Herein, the sine wave table stores sine waves in accordance with thedifferential PCM method. That is, the sine wave table is accessed by anoutput of the addition circuit; therefore, it is possible to outputmodulated waves having frequencies corresponding to the musical tonedata ωc1 or ωc2, as follows:A sin(ωc1t+B sin ωmt) orA sin(ωc2t+B sin ωmt)Then, an accumulator 7 accumulates data sequentially output from theoperator 6 to form musical tone signals (or digital sound signals).

In the aforementioned configuration of FIG. 1, tone color data ωm isapplied to the terminal T1; ‘1’ signal is applied to the terminal T3;and musical tone data ωc1 that is varied sequentially in response to amelody is applied to the terminal T2. Thus, the accumulator 7 outputsmonophonic musical tone signals having a tone color corresponding to thetone color data ωm in response to the musical tone data ωc1. If ‘0’signal is applied to the terminal T3, the accumulator 7 outputsmonophonic musical tone signals in response to an output of the musicaltone data conversion circuit 2, namely, musical tone data ωc2 that isslightly varied in value compared with the musical tone data ωc1. Thatis, it is possible to output musical tone signals that are slightlyshifted in pitches compared with musical tone signals based on themusical tone data ωc1.

The present embodiment provides a periodic signal Sa that isperiodically changed in value between ‘1’ and ‘0’ by the prescribedfrequency of 50 kHz, for example. When such a periodic signal Sa isapplied to the terminal T3, the sound source circuit 1 alternatelygenerates musical tone signals based on the musical tone data ωc1 andmusical tone signals based on the musical tone data ωc2 by short periodsrespectively. In other words, the accumulator 7 outputs musical tonesignals having a chorus effect that is substantially identical to theforegoing chorus effect imparted by the effector installed in anelectronic musical instrument or the like. Incidentally, as the periodicsignal Sa, it is possible to use a signal having a sampling frequency fsof musical tone data.

FIG. 2A shows an example of a waveshape of input musical tone datahaving a frequency f, which is input to the musical tone data conversioncircuit 2 realizing a frequency increment α. FIG. 2B shows an example ofa waveshape of output musical tone data having a frequency f+α, which isoutput from the musical tone data conversion circuit 2. Thus, the soundsource circuit 1 alternately outputs musical tone signals having thefrequency f and musical tone signals having the frequency f+α.

According to the present embodiment, it is possible to obtain musicaltone signals having a prescribed chorus effect with a very simpleconfiguration.

Incidentally, the sound source circuit 1 can be modified to replace themusical tone data conversion circuit 2 and selector 4 with an adder 8having three input terminals shown in FIG. 3. Herein, musical tone dataωc1 is applied to a first input terminal A; ‘0’ is applied to a secondinput terminal B; and a periodic signal Sa is applied to a carry-interminal CI. When the periodic signal Sa is ‘0’, the accumulator 7outputs musical tone signals based on the musical tone data ωc1 outputfrom the adder 8. When the periodic signal Sa is ‘1’, the accumulator 7outputs musical tone signals based on addition results of the adder 8 inwhich ‘1’ is added to the musical tone data ωc1.

In addition, the sound source circuit 1 can be modified to replace themusical tone data conversion circuit 2 and selector 4 with anexclusive-or circuit 9 having two inputs shown in FIG. 4. Herein, afirst input of the exclusive-or circuit 9 corresponds to an LSB (i.e., aleast significant bit) of the musical tone data ωc1, while a secondinput corresponds to the periodic signal Sa. An output of theexclusive-or circuit 9 is added to the musical tone data ωc1 as itsleast significant bit. Thus, when the periodic signal Sa is ‘1’, theleast significant bit of the musical tone data ωc1 is inverted by theexclusive-or circuit 9. When the periodic signal Sa is ‘0’, the leastsignificant bit of the musical tone data ωc1 is unchanged. Thus, it ispossible to impart a chorus effect to musical tone signals.

Further, the sound source circuit 1 can be modified to replace themusical tone data conversion circuit 2 and selector 4 with multiplemusical tone data conversion circuits 10 a, 10 b, 10 c, . . . , and aselector 11 which are shown in FIG. 5. Herein, each of the musical tonedata conversion circuits provides a prescribed frequency increment ordecrement with respect to an original frequency f of the musical tonedata ωc1 input thereto. That is, they convert the musical tone data ωc1having the frequency f to musical tone data having prescribedfrequencies each of which slightly differs from the original frequencyf. For example, the musical tone data conversion circuits 10 a, 10 b,and 10 c respectively provide converted frequencies of f+α, f+β and f+γ.The selector 11 sequentially selects the musical tone data ωc1 of theterminal T2 and outputs of the musical tone data conversion circuits 10a, 10 b, 10 c, . . . by prescribed periods, so that selected one isforwarded to the operator 6. Using such a configuration of FIG. 5, it ispossible to realize diversity in chorus effects imparted to musicaltones.

In FIG. 1, the selector 4 is not necessarily designed to alternatelyselect the musical tone data ωc1 applied to the terminal T2 and themusical tone data ωc2 output from the musical tone data conversioncircuit 2. That is, the selector 4 can be modified to arbitrarily setthe number of times for selecting one of them. For example, the musicaltone data ωc1 is selected three times while the musical tone data ωc2output from the musical tone data conversion circuit 2 is selected onlyone time. Thus, it is possible to arbitrarily change a frequency ofselecting the output data of the musical tone data conversion circuit 2while selecting the musical tone data ωc1 the prescribed number oftimes.

In addition, the musical tone data conversion circuit 2 provides anoutput frequency f+α (where f denotes an original frequency of themusical tone data ωc1), which can be changed to 2f representing anovertone in a harmonics series. In the case of 2f, the sound sourcecircuit 1 realizes so-called octave execution.

The present embodiment is designed to form musical tone signals inaccordance with the FM modulation method. This invention is notnecessarily limited to use the FM modulation method. Hence, it ispossible to use other methods for formation of musical tone signals suchas the PCM method (or wave memory method).

Next, a second embodiment of this invention will be described withreference to FIGS. 6 and 7, which show a configuration of a portabletelephone (namely, telephone terminal) that uses the sound sourcecircuit 1 shown in FIG. 1. In FIG. 6, a CPU (central processing unit) 12controls several parts and components of the portable telephone. A ROM13 stores programs run by the CPU 12 as well as tone color data andmusical tone data. Herein, there are provided two kinds of tone colordata, namely, a tone color of ringing incoming call sound representingincoming calls and a tone color of hold sound for notifying a callingparty of a hold event. In addition, a RAM 14 is provided to temporarilystore various data. Further, a display 15 is constituted by a small-sizeliquid crystal display. Furthermore, an input section 16 is constitutedby a ten-key unit and function keys.

A communicator 17 transmits signals on carrier waves via an antenna 18.In addition, the communicator 17 receives signals via the antenna 18 todemodulate and output them to a speech processor 19. The speechprocessor 19 decodes coded speech signals output from the communicator17 and converts them to analog signals, which are forwarded to a musicaltone playback circuit 21. In addition, the speech processor 19 encodesspeech signals output from a microphone 20 to output them to thecommunicator 17.

The musical tone playback circuit 21 generates the aforementionedincoming call sound and hold sound. Details will be described withreference to FIG. 7. Herein, an interface circuit 24 receives data givenfrom the CPU 12 via a bus B and sends them to a controller 25. That is,the controller 25 receives tone color data representing tone colors ofincoming call sound and hold sound as well as corresponding musical tonedata from the CPU 12 via the interface circuit 24. The tone color dataare stored in an internal memory of the controller 25; and the musicaltone data are stored in a RAM 26. When the CPU 12 issues an incomingcall sound generation instruction, the controller 25 sets the tone colordata of the incoming call sound to a sound source circuit 1. Then, itsequentially reads the musical tone data from the RAM 26 to send them tothe sound source circuit 1. In addition, the controller 25 outputs aperiodic signal Sa, which is produced by a system clock (not shown), tothe sound source circuit 1. Thus, a prescribed chorus effect is impartedto the musical tone data related to the incoming call sound in the soundsource circuit 1, which in turn outputs chorus-effect imparted musicaltone data to a digital-to-analog converter (DAC) 28. The DAC 28 convertsoutput data of the sound source circuit 1 to analog signals, which aresupplied to a speaker 31 by way of a buffer 30. Thus, the speaker 30produces the incoming call sound. In this case, a buffer 32 is placed inan OFF state in response to the incoming call sound generationinstruction.

When the CPU 12 issues a hold sound generation instruction, thecontroller 25 sets the tone color data of the hold sound to the soundsource circuit 1. Then, the controller 25 sequentially reads the musicaltone data from the RAM 26 to send them to the sound source circuit 1. Inaddition, the controller 25 outputs a periodic signal Sa to the soundsource circuit 1. Thus, a prescribed chorus effect is imparted to themusical tone data related to the hold sound in the sound source circuit1, which in turn outputs chorus-effect imparted musical tone data to theDAC 28. The DAC 28 converts output data of the sound source circuit 1 toanalog signals, which are supplied to a speaker 34 by way of the buffer32 and a mixing circuit 33. Thus, the speaker 34 produces the holdsound. In this case, the buffer 30 is placed in an OFF state in responseto the hold sound generation instruction. The musical tone data of thehold sound output from the sound source circuit 1 is also delivered tothe communicator 17 by way of the speech processor 19, so that thecommunicator 17 transmits it to the calling party. Incidentally,reference numeral 35 designates a buffer that amplifies speech signalssupplied from the speech processor 19.

According to the present embodiment, the portable telephone does notproduce monophonic melody sound but is able to produce chorus-effectimparted melody sound as the incoming call sound and hang-on sound.Thus, it is possible to produce comfortable and pleasant melody sound,which is heard not only by the user of the portable telephone but alsoby persons around the user and by the calling party who listens to thehold sound.

As described heretofore, this invention provides a simple configurationfor realizing chorus effects in generation of incoming call sound andhold sound of the portable telephone without using an effector which iscomplicated and expensive. There are provided at least two kinds ofmusical tone data, namely, original musical tone data ωc1, andpitch-modified musical tone data ωc2, which is slightly modified inpitch as compared with the original musical tone data, with respect tothe prescribed tone color. These musical tone data are periodicallyselected by each prescribed period and are subjected to synthesis (e.g.,addition or accumulation) to form musical tone signals having a choruseffect, based on which chorus-effect imparted musical tones are producedwith diversity and variety of sound.

Lastly, this invention is not necessarily limited to the aforementionedembodiments, so this invention may be embodied in other forms withoutdeparting from the spirit of essential characteristics thereof

1. A portable telephone terminal that generates an incoming call soundbased on an incoming call or that generates a hold sound based on a holdsound reproduction instruction, said portable terminal comprising: astorage device for storing musical tone data representing tone pitchesof musical tones; a control device for sequentially reading the musicaltone data from the storage device; a sound source circuit for generatingmusical tone signals based on the read musical tone data; and a musicaltone generation device for generating the incoming call sound or thehold sound based on the musical tone signals, wherein said sound sourcecircuit includes: a conversion device to convert first musical tone datarepresenting a first tone pitch, which is read by the control device,into second musical tone data representing a second tone pitch, whichdiffers from the first tone pitch; a periodic signal generation deviceto generate a periodic signal having a high frequency; a selectiondevice to alternately select the first musical tone data and the secondmusical tone data in response to the periodic signal; and a musical tonesignal formation device to produce modulated waves having frequenciescorresponding to the first musical tone data and the second musical tonedata, which are alternatively selected by the selection device, thusforming musical tone signals, wherein the musical tone signal formationdevice alternatively and repeatedly outputs the modulated wave havingthe frequency of the first musical tone data and the modulated wavehaving the frequency of the second musical tone data based on a periodof the periodic signal.
 2. The portable telephone terminal according toclaim 1, wherein the frequency of the periodic signal corresponds to asampling frequency (fs) of the musical tone signals.
 3. A portabletelephone terminal that generates an incoming call sound based on anincoming call or that generates a hold sound based on a hold soundreproduction instruction, said portable terminal comprising: a storagedevice for storing musical tone data representing tone pitches ofmusical tones; a control device for sequentially reading the musicaltone data from the storage device; a sound source circuit for generatingmusical tone signals based on the read musical tone data; and a musicaltone generation device for generating the incoming call sound or thehold sound based on the musical tone signals, wherein said sound sourcecircuit includes: a data processing device to alternately perform at ahigh frequency a first process to directly transfer first musical tonedata, provided from an external source, designating a first tone pitch,and a second process to convert the first musical tone data to secondmusical tone data designating a second tone pitch that differs from thefirst tone pitch; and a musical tone signal formation device forproducing modulated waves having frequencies corresponding to the firstmusical tone data and the second musical tone data, which arealternatively processed by the data processing device, thus formingmusical tone signals, wherein the musical tone signal formation devicealternatively and repeatedly outputs the modulated wave having thefrequency of the first musical tone data and the modulated wave havingthe frequency of the second musical tone data based on a period of theperiodic signal.
 4. The portable telephone terminal according to claim3, wherein the data processing device includes an exclusive or circuitthat inverts a least significant bit of the first musical tone data bythe periodic signal.
 5. The portable telephone terminal according toclaim 3, wherein the data processing device includes an addition circuitthat alternately adds zero and a prescribed value to the first musicaltone data.
 6. A portable telephone terminal that generates an incomingcall sound based on an incoming call or that generates a hold soundbased on a hold sound reproduction instruction, said portable terminalcomprising: a storage device for storing musical tone data representingtone pitches of musical tones; a control device for sequentially readingthe musical tone data from the storage device; a sound source circuitfor generating musical tone signals based on the read musical tone data;and a musical tone generation device for generating the incoming callsound or the hold sound based on the musical tone signals, wherein saidsound source circuit includes: a conversion device to convert firstmusical tone data, provided from an external source, designating a firsttone pitch to second to n-th musical tone data (where ‘n’ denotes anintegral number) designating second to n-th tone pitches each slightlydiffering from the first tone pitch; a periodic signal generation deviceto generate a periodic signal having a high frequency; a selectiondevice to sequentially select and output the first to n-th musical tonedata in response to the periodic signal; and a musical tone signalformation device to produce modulated waves having frequenciescorresponding to first to n-th musical tone data, which areconsecutively output by the selection device, thus forming musical tonesignals, wherein the musical tone formation device consecutively outputsthe modulated waves having the frequencies corresponding to the first ton-th musical tone data based on a period of the periodic signal.
 7. Theportable telephone terminal according to claim 6, wherein the frequencyof the periodic signal corresponds to a sampling frequency (fs) of themusical tone signals.